Adaptive Output Feedback Control for Uncertain Nonlinear Systems Subject to Deferred State Constraints

This paper addresses the tracking control problem for a class of uncertain nonlinear systems with full state deferred constraints. The constraints considered occur after a period of system operation rather than from the beginning. An attempt has been made to use a shifting function to realize the purpose of deferred constraint. Moreover, the difficulty of asymmetric constraint on states comes from the design on barrier function. Due to this, an unified barrier function is proposed to prevent system states from violating the constraint range, indirectly. Meanwhile, it effectively removes the restriction condition used in existing results that the upper and lower bound signs of constraint functions are the same. Consequently, the goals of tracking a reference signal and state constraints are achieved through the control scheme designed. Theoretical analysis and simulations are presented to demonstrate the efficacy of the proposed control strategy.